Problem: The ratio of the areas of two concentric circles is 1:3. If the radius of the smaller is r, then the difference between the radii is best approximated by:
Answer Choices:
A. 0.41r
B. 0.73
C. 0.75
D. 0.73r
E. 0.75r
Solution:
Let x be the radius of the larger circle. Then πr2/πx2=1/3,x=r3​, r3​−r=r(3​−1)∼0.73r.